Reactions of Phenyllithium with the Stannylene Ar*SnPh (Ar* = C₆H₃-2,6-Trip₂; Trip = C₆H₂-2,4,6-Prⁱ₃) and the Synthesis of the Distannylstannylene Sn(SnPh₂Ar*)₂:  Contrasting Behavior in Methyl and Phenyl Derivatives

The reaction of LiPh with Ar*SnPh (Ar* = C₆H₃-2,6-Trip₂; Trip = C₆H₂-2,4,6-Prⁱ₃) afforded either the monomeric etherate (Et₂O)LiSnPh₂Ar* (1) or the dimer (LiSnPh₂Ar*)₂ (2). The reaction of 2 with SnCl₂ in a 1:1 ratio in Et₂O yielded the monomeric distannylstannylene Sn(SnPh₂Ar*)₂ (3). The compounds 1−3 were characterized by ¹H, ⁷Li, ¹³C, and ¹¹⁹Sn NMR and UV−vis spectroscopy. Complete single-crystal X-ray crystal structures of 2 and 3 were determined as well as a partial structure for 1. The structure of 1 showed that the tin was pyramidally coordinated by the three organic groups as well as by lithium. The lithium was found to be ligated by ether and η⁶-coordinated by one of the phenyl rings. The structure of 2 showed that it was dimerized through η⁶-interactions of a tin-coordinated lithium with a phenyl group of a partner monomer rather than through tin−tin bonding. The structure of 3 featured a central, two-coordinate tin(II) bound to two SnPh₂Ar* groups with long Sn−Sn distances near 2.96 Å and a very wide Sn−Sn−Sn angle of 115.19(2)°. The ¹¹⁹Sn NMR chemical shift of the central tin is 3752 ppm, which is the furthest downfield ¹¹⁹Sn NMR chemical shift recorded for a stannylene.